Advances in biotechnology and immunology have presented new challenges for obtaining safe and effective drugs, such as vaccines. For example, new generation subunit and antiidiotype antigens yield very safe vaccines; however, these vaccines, in general, provide poor immune stimulation and prophylactic effects. Therefore, an important aspect of any new drug or vaccine formulation is a component that enhances its safety and efficacy by providing a delivery mechanism and, in the case of vaccines, by boosting the immune response to the antigen. Adjuvants can generally be categorized as components that boost the immune response, and as delivery systems that enhance antigen presentation, provide sustained release of the drug or antigen for extended periods, or target the drug or antigen to specific immune cells.
Serious drawbacks exist in many of today's adjuvants and delivery systems. Most are crude preparations of bacterial or plant origin, or oil emulsion systems, the active components and modes of action of which are unknown. In addition, these compounds are usually toxic and cannot be used safely, especially for human applications. Some preparations of the yeast cell wall component, .beta.-glucan have been shown to provide enhanced resistance to several infectious diseases when given in conjunction with viral vaccines or killed infected cells. Reynolds et al., 1980. Infect. Immunity, 30:51-57; Holbrook et al., 1981, Infect. Immunity, 35:534-546; Benach et al., 1982, Infect. Immunity, 36:947-951. Some of the adverse effects of administering other .beta.-glucan preparations are described by Williams et al. in U.S. Pat. No. 4,761,402. These effects include anaphylaxis, granuloma development, hypotension development and a high degree of acute toxicity.